From wiki.openlighting.org

DMX 4 Linux has been the de-facto library for communicating with DMX devices under Linux.
Supporting over 14 DMX interfaces including PCI, USB and parallel port models, the DMX 4 Linux architecture is easily extensible.

Alternatives include the driver framework OLA (with many DMX over IP protocols) and the controller app QLC that directly supports EnttecOpen DMX USBAnyma uDMX , and with a special kernel module the Rodin1.

DMX 4 Linux 2.6 Release
Development snapshots for 2.6 kernels from the dmx4linux developers are here

Bastien Andres has made an unofficial release of DMX 4 Linux for the 2.6 series of kernels. A number of drivers have been modified to compile cleanly on 2.6 and the build system has also been cleaned.

Some drivers do not compile or are incomplete, see the STATUS_BA file in the archive for more details. Sources available here